Check boxes within an editable PDF

Hi all,

I've made some editable forms (in Adobe PRO DC) - all going super well EXCEPT ...  I have a page with multiple check boxes (have these experienced this that or the other health condition - as part of a registration form) but when I email it to myself to check it, all the boxes are already checked.

I right-clicked the properties & notice there is a check box you can select if you WANT them all to be ticked already, but I definitely don't have this ticked.  I also ticked 'locked' in that box, but they are still all ticked.

Is it something to do with a checkbox earlier being selected that automatically selects all these?

Any help would be gratefully received.

Many thanks,

Caro